1. Technical Field of the Invention
The present invention relates to a starter for starting an engine, which includes a motor and a minimized electromagnetic switch working to operate electric power supply to the motor.
2. Description of the Related Art
Conventionally, a starter for starting an engine generally includes a motor and an electromagnetic switch that is disposed close to and radially outward of the motor and works to operate main contacts of a motor circuit.
More specifically, the electromagnetic switch includes a solenoid, a pair of fixed contacts that serve as the main contacts of the motor circuit, and a movable contact. The solenoid includes an electromagnetic coil and a plunger. The fixed contacts are connected to the motor circuit through a pair of terminal bolts.
When the electromagnetic coil is energized, the plunger is attracted by a magnetic attraction to move the movable contact, thereby causing the movable contact to bridge or electrically connect the fixed contacts. As a result, the motor circuit is closed to supply electric power from a battery to the motor.
On the contrary, when the electromagnetic coil is deenergized, the magnetic attraction disappears, causing the plunger and the movable contact to return to their initial positions. As a result, the fixed contacts are electrically disconnected, so that the motor circuit is opened and the electric power supply to the motor is thus interrupted.
Further, Japanese Patent No. 3478211 discloses an electromagnetic switch for a starter, in which the fixed contacts are integrally formed with the terminal bolts, respectively. One of the terminal bolts is electrically connected to the battery via a battery cable; the other is electrically connected to a lead taken out from the motor. Both the terminal bolts are fixed to a resin-made contacts cover.
However, in the above electromagnetic switch, the terminal bolts are arranged to extend in the axial direction of the motor and align with each other in the radial direction of the motor. Accordingly, it is difficult to minimize the electromagnetic switch in the radial direction of the motor.
More specifically, it is necessary to secure a sufficient insulation distance between the two terminal bolts, and thus there is a limit to closely disposing them in the radial direction. Further, it is also necessary to secure a sufficient distance between the two terminal bolts, so as to prevent an insulator that retains the movable contact from interfering with the fixed contacts when the movable contact makes contact with the fixed contacts. Therefore, it is difficult to minimize the electromagnetic switch in the radial direction of the motor, even if the other parts of the electromagnetic switch can be individually minimized.